Our present invention relates to a process for direct metallization of a nonconductor.
Coatings or layers on nonconductors, which are made of electrically conductive heterocyclic polymers, are known in themselves. These heterocyclic polymer coatings or layers are described in German Patent 3,520,980, German Patent 3,132,218 and 3,535,709 as well as European Patent 0,206,133. A polypyrrole coating or layer can be formed on a nonconductor from a monomeric pyrrole using a strong oxidizing agent. These conducting nonconductors form the basis of the subject matter of the present application.
The use of polymers with an intrinsic electrical conductivity, which are formed from a monomer and a strong oxidizing agent, for making the electrical through-going contacts in circuit boards, is described in an additional German Patent Document(DE 3,806,884 C1).
The use of the methods of EP 0,206,133 and German patent 3,806,884 require use of a strong acid and a strong oxidizing agent. These methods also require a high degree of technical engineering skill, so that the range of practical usages, in which the desired results are obtained, is very narrow.
Undesirable side reactions of heterocyclics being used also occur, since pyrroles are especially easily polymerized by light or acid. The acids have the power to form an insoluble black precipitate from the polypyrrole formed from the monomers in a short time. This precipitate is amorphous and cannot be processed further.